A disk drive, such as a magnetic disk drive, comprises a magnetic disk for use as a recording medium, a spindle motor, a magnetic head, and a carriage assembly. The magnetic disk is disposed in a case. The spindle motor supports and rotates the magnetic disk. The magnetic head reads data from and writes data to the magnetic disk. The carriage assembly supports the head for movement relative to the magnetic disk. The magnetic head comprises a slider mounted on a suspension of the carriage assembly and a head section on the slider. The head section comprises a recording element for writing and a reproduction element for reading.
The head slider comprises a bearing surface (air-bearing surface or ABS) opposed to a recording surface of the magnetic disk. The head slider is subjected to a predetermined head load produced by the suspension and directed to a magnetic recording layer of the magnetic disk. When the magnetic disk drive is operating, an airflow is produced between the rotating disk and head slider, and the ABS of the slider is subjected to a force (positive pressure) that causes the slider to fly relative to the recording surface of the disk, based on the principle of air lubrication. The head slider is caused to fly over the recording surface of the magnetic disk, with a gap therebetween, by balancing this flying force with the head load.
In recent years, to meet the demand for greater recording density, increasing importance has been attached to reduction of head flying height and flying-height control in a low-height area, and development of technologies for dynamically controlling the head flying height has advanced rapidly. Presently, the flying gap between a magnetic disk and the head slider of a magnetic head in the vicinity of a read/write element is 10 nm or less. Further, for read/write operations, the gap between the read/write element and the magnetic disk is reduced to approximately several nanometers by additionally using a dynamic flying height (DFH) technology in which the magnetic spacing is controlled by dynamically adjusting the projection of the read/write element.
As a result, certain problems have become apparent. For example, a lubricant applied to the disk surface is transferred to the ABS of the head slider flying above the magnetic disk, the magnetic spacing is increased, and the flying performance of the head slider is made unstable.
The lubricant transferred to the ABS of the head slider of the magnetic head is moved onto the air-outflow end surface of the head slider by the airflow and accumulates there. If the transferred lubricant accumulates excessively, the flying height of the head slider becomes unstable. Thereupon, a high-fly write (HFW) problem occurs in which the recording and reproduction signals become unstable. Further, there is a problem wherein the reproduction signals vary when the magnetic disk drive is started up, since the lubricant diffuses and returns to the read/write element portion on the ABS side while the magnetic head is in an unloaded state with the disk drive off.